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arXiv · 2203.00566

Measuring the propagation speed of gravitational waves with LISA

Tessa Baker·Gianluca Calcagni·Anson Chen·Matteo Fasiello·Lucas Lombriser·Katarina Martinovic·Mauro Pieroni·Mairi Sakellariadou·Gianmassimo Tasinato·Daniele Bertacca·Ippocratis D. Saltas
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Abstract

The propagation speed of gravitational waves, $c_T$, has been tightly constrained by the binary neutron star merger GW170817 and its electromagnetic counterpart, under the assumption of a frequency-independent $c_T$. Drawing upon arguments from Effective Field Theory and quantum gravity, we discuss the possibility that modifications of General Relativity allow for transient deviations of $c_T$ from the speed of light at frequencies well below the band of current ground-based detectors. We motivate two representative Ansätze for $c_T(f)$, and study their impact upon the gravitational waveforms of massive black hole binary mergers detectable by the LISA mission. We forecast the constraints on $c_T(f)$ obtainable from individual systems and a population of sources, from both inspiral and a full inspiral-merger-ringdown waveform. We show that LISA will enable us to place stringent independent bounds on departures from General Relativity in unexplored low-frequency regimes, even in the absence of an electromagnetic counterpart.

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Tessa Baker, Gianluca Calcagni, Anson Chen, Matteo Fasiello, Lucas Lombriser, Katarina Martinovic, Mauro Pieroni, Mairi Sakellariadou, Gianmassimo Tasinato, Daniele Bertacca, Ippocratis D. Saltas. 2022-07-13. Measuring the propagation speed of gravitational waves with LISA. https://doi.org/10.1088/1475-7516%2F2022%2F08%2F031

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